If you upgrade to php5.5.2/pcre7.0, and fillInFormValues stops working, you've get a version of pcre (7.0) that doesn't like one of the regular expressions used by fillInFormValues.

Upgrade your version of pcre (painful, because you've got to recompile php) to fix. Or downgrade back to a version of php that doesn't use pcre7.0, and wait for a version of PHP that contains the fixed PCRE.